* Add `DALEC_CALDAV_SERCH_EVENT_START_TIMEDELTA` and `DALEC_CALDAV_SERCH_EVENT_END_TIMEDELTA`
settings. Default values are respectively -1 day and +365 days.
It could be a breaking change if the real behaviour you expected was to only keep only the X
oldest events. (`X` depending the settings). If you want to continue to fetch all events, you
can set those settings to `None`.
* Improve tests with ICS files containing different test cases
* Add the hability to test with other external caldav servers to be sure that this Dalec will work
with your specific caldav server.